DIY porting a inlet manifold.
Discussion
Some pictures of my latest attempts a producing the ideal 4.5 AJP inlet for road use. Started with a second hand 4.2 cast manifold with 45mm throttles. This shows the original manifold to head port.
After about 2 days of hand grinding and polishing with got these ports to look like this
Wanted to use 48mm throttles so had the 45mm ports bored out by a machine shop to 48mm
The manifold wall thickness is just sufficient to take the increase in size on the straight section of the inlet but care must be taken not to bore to deep. You can see the increase in size with the step at the bottom.
carefully by hand removed the step left over from the machining...takes bloody ages as you must keep checking the wall thickness. Flowed the complete length of the inlet tracks using coarse/medium/fine lapping wheels so that it ended up like this
Fitted 48mm butterlies from a webber carbs. £5.00 each Thinned the throttle spindles down and countersunk all the screws.
Took about 40hrs in total cost including manifolds and machining £400.00.
Will It work or make a difference...I havent a clue as I will not be fitting it just yet. Just thought it would make an interesting thread.
After about 2 days of hand grinding and polishing with got these ports to look like this
Wanted to use 48mm throttles so had the 45mm ports bored out by a machine shop to 48mm
The manifold wall thickness is just sufficient to take the increase in size on the straight section of the inlet but care must be taken not to bore to deep. You can see the increase in size with the step at the bottom.
carefully by hand removed the step left over from the machining...takes bloody ages as you must keep checking the wall thickness. Flowed the complete length of the inlet tracks using coarse/medium/fine lapping wheels so that it ended up like this
Fitted 48mm butterlies from a webber carbs. £5.00 each Thinned the throttle spindles down and countersunk all the screws.
Took about 40hrs in total cost including manifolds and machining £400.00.
Will It work or make a difference...I havent a clue as I will not be fitting it just yet. Just thought it would make an interesting thread.
The whole length of the inlet port was enlarged to at least the same size as the outlet. This was done with lapping wheels of various grades and diameters and a very flexible but stong drive. It does take a long time but the material casting is quiet soft so removing metal is not difficult.
It is a matter of just constantly passing the wheel up and down the inlet port. There are tight spots at first and the surface finish and flashings of the original casting is poor but after several hours on each inlet tract the same diameter wheel passes from the outlet/cylinder port right up around the bend until it naturally enlarges where the throttle butterfly is located. The wall thickness is very thin and varies along its length, at some parts its only around 1.5mm. I did break through the wall on one bend but hopefully have recovered the situation by getting the hole welded and then dressing the area afterwards.
Even the spindles and butterflys on the original are poorly assembled and can benifit from simply good re-engineering.
This is part of my project to get at least 500BHP out of the my 4.5, the other part has just arrived from the states that should help see below
Its a vortech V2 supercharger which I want to fit running low boost, now I know this will raise all sorts of opinions as I started a thread earlier in the year but I'm going to try anyway...If it dosent work then there will be a cheap nearly new supercharger on fleebay next year.
Any comments, help and advise on this project will be happily accepted.
Any ideas on who would be willing to map the engine?
It is a matter of just constantly passing the wheel up and down the inlet port. There are tight spots at first and the surface finish and flashings of the original casting is poor but after several hours on each inlet tract the same diameter wheel passes from the outlet/cylinder port right up around the bend until it naturally enlarges where the throttle butterfly is located. The wall thickness is very thin and varies along its length, at some parts its only around 1.5mm. I did break through the wall on one bend but hopefully have recovered the situation by getting the hole welded and then dressing the area afterwards.
Even the spindles and butterflys on the original are poorly assembled and can benifit from simply good re-engineering.
This is part of my project to get at least 500BHP out of the my 4.5, the other part has just arrived from the states that should help see below
Its a vortech V2 supercharger which I want to fit running low boost, now I know this will raise all sorts of opinions as I started a thread earlier in the year but I'm going to try anyway...If it dosent work then there will be a cheap nearly new supercharger on fleebay next year.
Any comments, help and advise on this project will be happily accepted.
Any ideas on who would be willing to map the engine?
Fantastic project, supercharger looks awesome. 
You'll lose some charge from the large cam overlap if you stay with the original cams, but the V2 will be more than able to make up for that. Driven off the air con pulley, I take it??
Charge cooling would be an easier fit than an air to air intercooler, you'll struggle getting the large bore pipes past the radiator. IIRC Vortech do a chargecooler??
Craigs NOS cerb pushed over 500 horses without issue, key is to keep the temps low, its worth a try without spending thousands on a bottom end, before you know it you'll have a Phoenix project on your hands
Set your power goals and stick to them, don't get greedy 
Well impressed with the throttles, is 1.5mm thick, OK for taking a bit of pressure though??
Rich.
You'll lose some charge from the large cam overlap if you stay with the original cams, but the V2 will be more than able to make up for that. Driven off the air con pulley, I take it??
Charge cooling would be an easier fit than an air to air intercooler, you'll struggle getting the large bore pipes past the radiator. IIRC Vortech do a chargecooler??
Craigs NOS cerb pushed over 500 horses without issue, key is to keep the temps low, its worth a try without spending thousands on a bottom end, before you know it you'll have a Phoenix project on your hands
Set your power goals and stick to them, don't get greedy Well impressed with the throttles, is 1.5mm thick, OK for taking a bit of pressure though??
Rich.
Gazzab said:
itiejim said:
Looks like a fantastic project - good luck!
I'd give it to Dave Walker at Emerald to map (using his ECU).
does daves rr go to such high hp?I'd give it to Dave Walker at Emerald to map (using his ECU).
Sorry to labour the point but I find this part of the actual mechanics quite interesting. To do it at all properly would require IMHO, cutting the inlet in two on the curve, then porting, then seam welding at the end.
I'm not sure how passing a flap wheel no matter how clever would do anything other than have all its pressure at the outer ridge, unless the flap wheel was in some clever guiding cage.
That leaves you with the problem of knowing how thick you were making the exterior wall, which would require ?xray/USS? So not sure how they could be sure of the 1.5mm, or to be honest anything rearding the deep dark curve.
Would be truly interested to find out.
I'm not sure how passing a flap wheel no matter how clever would do anything other than have all its pressure at the outer ridge, unless the flap wheel was in some clever guiding cage.
That leaves you with the problem of knowing how thick you were making the exterior wall, which would require ?xray/USS? So not sure how they could be sure of the 1.5mm, or to be honest anything rearding the deep dark curve.
Would be truly interested to find out.
I think you are over complicating the process. It is easy to measure the wall thikness with a pair of external calipers, You can use internal calipers to compare bore sizes from one port to the other so that there is a partial level of accuracy between different tracts.
I used about 20 different flap wheels of different sizes and grades. When these spin at a high speed they remove metal very evenly from a round hole.
Around the bend was the most difficult section smaller diameter wheels were used at first then I slowly increased them in size. The metal was removed quite evenly. You could see the rough casting being polished slowly away on an even basis.
The most important piece of kit was a home made flexible drive. The flexible drives that you can purchase are not flexible at the end where the tool is due to the chuck and the handle. I modified a flexible socket extension to hold the flap wheels this allowed me to push and pull the flap wheels up and down the tract along its whole length.
I know its not perfect and I would do things differently a second time but large amounts of metal have been removed. The surface is nicely polished rather than the rough cast finish and it "appears" to be a big improvement over the original.
I will post some more pictures up friday/saturday
I used about 20 different flap wheels of different sizes and grades. When these spin at a high speed they remove metal very evenly from a round hole.
Around the bend was the most difficult section smaller diameter wheels were used at first then I slowly increased them in size. The metal was removed quite evenly. You could see the rough casting being polished slowly away on an even basis.
The most important piece of kit was a home made flexible drive. The flexible drives that you can purchase are not flexible at the end where the tool is due to the chuck and the handle. I modified a flexible socket extension to hold the flap wheels this allowed me to push and pull the flap wheels up and down the tract along its whole length.
I know its not perfect and I would do things differently a second time but large amounts of metal have been removed. The surface is nicely polished rather than the rough cast finish and it "appears" to be a big improvement over the original.
I will post some more pictures up friday/saturday
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